Revert "fix: default env substitution only AFTER sourcing the namespaced env"

This reverts commit 2492281.

Author: SwaroopH

configure-environment.sh

@@ -946,12 +946,12 @@ main() {
         exit 1
     fi
 
-    # Source the environment file to ensure all variables are available for validation
-    source "$ENV_FILE_PATH"
-
     # Set default optional variables
     set_default_optional_variables "$ENV_FILE_PATH"
 
+    # Source the environment file to ensure all variables are available for validation
+    source "$ENV_FILE_PATH"
+    
     # Validate environment
     validate_environment